Improvement in sewing-machines



2 shets sheet 2. G. GRUU BMAN.

Sewing-Machines. N0,l56,728 .7 I Y Patented Nov. 10,1874.

THE GRAPHIC C0. FHOTDLXTILBQ 8K4! PARK PLACEJLY- UNITED STATES PATENT OFFICE.

CHAIM GROUBMAN, OF ODESSA, RUSSIA.

IMPROVEMENT IN SEWING-MACHINES.

Specification forming part of Letters Patent No. 156,728, dated November 10, 1874; application filed July 25, 1874.

To all whom it may concern:

Be it known that I, CHAIM GROUBMAN, of Odessa, in the Empire of Russia, temporarily of London, England, have invented a new and useful Improvement in Sewing-Machines; and I do hereby declare that the following is a full, clear, and exact description of the same, refercnce being had to the accompanying drawing, forming a part of this specification, in which Figure 1 is a front elevation of the machine, and Fig. 2 is an end elevation of the same.

The invention is an improvement in the class of sewing-machines Whose needle-bars are connected with an actuating rock-shaft by means of a wrist-pin and vibrating arm, the latter having a slot in its free end in which the pin works.

The object of the invention is to distribute the wear or friction incident to such connection of the needle-bar and rock-shaft arm over a larger surface, and to furnish a guide for the needle-bar in its reciprocating movement. I mount or pivot two rectangular blocks on the pin of the needle-bar, one of which slides vertically in a groove or slot of the head of the machine, and the other in the slot of the arm of the rock-shaft.

A is the bed-plate of the machine, and B the head or fixed arm of the frame. 0 is the main driving-shaft, mounted beneath the bed-plate A, carrying at one extremity the rotating looper D, and adapted to receive motion at the other end by a band from a treadle or other motor device, -(not shown.) E is the needle-bar working in guides in the head of the arm B. All these parts are constructed and operated in the usual manner. F is a rockshaft mounted in bearings G G fixed at the back of the arm B. To one extremity of this shaft is fixed a crank-arm, H, connected with the needle-bar E by a screwstud, I, fixed in the latter, passing through a slide-block, K, working in a slot, L, in the end of the arm H, and through a second slideblock, M, working up and down in a vertical slot or guide, N, in the head of the arm B. The block M serves to move the block K to and fro in the fork of crank-arm H as the latter is vibrated. The block K has a second motion imparted to it simultaneously with said to-and-fro motion, to wit, an oscillation on the screw-stud I, At the other end of the rockshaft F is fixed a crank-arm, O, coupled, by a connecting-rod, P, to a crank-pin, It, fixed on a disk keyed on the rotary driving-shaft 0, from which the rock-shaft F thus receives motion. The radius of the arm 0 being greater than that of the crank-pin R, the rotary motion of the latter imparts a rocking motion to the .shaft F, which imparts up-and-down motion Witnesses:

W. G. E. SWIMWELL, HY. SWALES. 

